Getter devices with non-evaporated gettering material, for maintaining vacuum in electronic tubes



Dec. 28, 1965 P. DELLA PORTA 3,225,910

GETTER DEVICES WITH NON-EVAPORATED GETTERING MATERIAL, FOR MAINTAININGVACUUM IN ELECTRONIC TUBES Filed April 13, 1961 FIG.3

United States Patent Ofitice 3,225,910 Patented Dec. 28, 1965 3 225 910GETTER DEVICES WITH NQN-EVAPORATED GET- TERIN G MATERIAL, FORMAINTAINING VACU- UM IN ELECTRGNIC TUBES Paolo Della Port-a, ViaGallarate 215, Milan, Italy Filed Apr. 13, 1961, Ser. No. 102,756 3Claims. (Cl. 206.4)

The object of this invention is to provide an improvement in getterdevices with a non-evaporated gettering material, for keeping vacuum inelectronic tubes; namely, in devices of the kind with non-evaporatedgettering material in tabloid shape.

As distinguished from known evaporated getter devices, in which thegettering material is completely evaporated and is deposited in theshape of a film on the walls of the electronic tube, which film has thetask of absorbing the gases developed in the electronic tube, with thenonevaporated getter the gettering material keeps its shape and absorbsthe gases developed in the electronic tube through its surface exposedto said gases. Consequently, the effectiveness of the non-evaporatedgetter depends not only on its composition, but also on the magnitude ofits surface exposed to the gases. The increase of the surface area ofthe gettering material, however, is hindered by the limitations existingfor the space requirement in practical application of getter devices inelectronic tubes.

It is an object of the present invention to improve getter devices withnon-evaporated gettering material in tabloid shape, either circular orparallelepiped, to the effect of increasing the surface area exposed togases, without increasing the space requirement of the device. Thatresult is attained according to the invention by creating supports forthe gettering material which leave said material exposed on both thelarger faces of the tabloid.

In the accompanying drawing there are illustrated by way of example someembodiments of the present invention, as follows:

FIG. 1 is a longitudinal section of a circular getter device;

FIG. 2 is a longitudinal section of a tabloid getter de vice; and

FIG. 3 is a top plan view of a strip support for tabloid getter devices.

FIG. 1 shows a circular getter device in the shape of a disc 3, of mixedtype; namely, containing within an external peripheral channel anevaporated gettering material 1 and at the centre of the disc a tabloidof non-evaporated gettering material 2. In the disc 3 there is providedat its centre, by means of punching, a central hole having the diameterof the tabloid of non-evaporated gettering material 2. The border 3' ofsuch hole is bent back in such a way as to constitute an anchorage forthe tabloid 2. The tabloid is directly pressed into the hole with such athickness that its surfaces 2, 2" are at lower level with respect to thecorresponding parts 3" of the disc, in such a way and for the purposethat the tabloid should remain protected against impacts during stockageand transport.

It is apparent that whatever is the position of the getter device in theelectronic tube, both surfaces of the tabloid 2 are exposed to the gasesdeveloped in said tube.

FIG. 2 shows a type of support for a tabloid of nonevaporated getteringmaterial 2, contained between two discs 4, 4" with central bores 6 and 6having diverging inner borders 7 and 7, respectively, forming a seat forthe correspondingly shaped border 8 of the tabloid 2. The tabloid 2 andthe bores 6 and 6' are geometrically complementary in shape, thediverging borders 7 and 7' of the said bores conformally receiving thebeveled border 8 of the tabloid 2. Both the larger surfaces of thetabloid remain exposed to the gases.

FIG. 3 shows a type of support constituted by a strip of metal gauze 5,or of expanded metal sheet, whereonto the tabloids of gettering materialare pressed. The tabloids may have any shape, for instance, circular 2a,square 2b or rectangular 2c. Also in this case the two surfaces of thetabloids remain exposed to the gases, since the supporting wire gauze 5does not form a substantial hindrance. This shape of the deviceaccording to FIG. 3 moreover has the advantage of permitting aconsiderable flexibility of the support and of permitting, therefore,the application thereof to the curved surfaces of the anode of theelectron tube. The production of this device may be carried out withautomatic machines wherein the wire gauze strip passes continuouslyunder magazines which are loaded with tabloids or with powder ofgettering material, and the tabloid or the powder is pressed directlyonto the supporting wire gauze. Subsequently the strip is cut to thedesired lengths for every individual getter device. In lieu of thetabloids of a certain thickness, applied on one side of the supportingwire gauze, it is possible, of course, also to apply two equal tabloids,having half thickness, contemporaneously at the two faces of the wiregauze. As a further embodiment of this concept, it is possible to applythe relatively thin tabloids on the two sides of a flexible support suchas a perforated or expanded metal tape in such a way that the twotabloids that are contemporaneously pressed against the tape, at oneside and at the other side thereof, join through the resultinginterstices in the tape and thereby remain attached to the support.

What I claim is:

1. In a getter device for maintaining a vacuum in electronic tubes, thecombination comprising a non-evaporable gettering means,

support means for said gettering means including a flat perforatedmetallic strip means,

said gettering means including a tabloid of compressed non-evaporablegettering material, said tabloid having a peripheral portion andoppositely disposed surface portions separated thereby,

said peripheral portion being formed integrally with said perforatedmetallic strip means through an interstice thereof,

each of said tabloid surface portions defining a surface area on oneside of said support means whereby said tabloid is exposed to gases onboth sides of said support means.

2. The invention defined in claim 1 wherein said flat perforatedmetallic strip means comprises a flexible strip of wire gauze.

3. The invention as defined in claim 1 wherein said flat perforatedmetallic strip means comprises a flexible strip of expanded metal.

References Cited by the Examiner UNITED STATES PATENTS 2,167,852 8/1939Rose 313-174 2,404,803 7/ 1946 Stafford 206-0.4 X 2,499,197 2/ 1950Posey 2060.4 X 2,547,200 4/1951 Dorgelo 313178 X FOREIGN PATENTS 552,8681/1960 Belgium.

975,603 3/ 1951 France.

879,429 6/ 1953 Germany. 1,079,746 4/ 1960 Germany.

830,319 3/1960 Great Britain.

THERON E. CONDON, Primary Examiner.

ARTHUR GAUSS, EARLE J. DRUMMOND,

Examiners.

1. IN A GETTER DEVICE FOR MAINTAINING A VACUUM IN ELECTRONIC TUBES, THECOMBINATION COMPRISING A NON-EVAPORABLE GETTERING MEANS, SUPPORT MEANSFOR SAID GETTERING MEANS INCLUDING A FLAT PERFORATED METALLIC STRIPMEANS, SAID GETTERING MEANS INCLUDING A TABLOID OF COMPRESSEDNON-EVAPORABLE GETTERING MATERIAL, SAID TABLOID HAVING A PERIPHERALPORTION AND OPPOSITELY DISPOSED SURFACE PORTIONS SEPARATED THEREBY, SAIDPERIPHERAL PORTION BEING FOMED INTEGRALLY WITH SAID PERFORATED METALLICSTRIP MEANS THROUGH AN INTERSTICE THEREOF, EACH OF SAID TABLOID SURFACEPORTIONS DEFINING A SURFACE AREA ON ONE SIDE OF SAID SUPPORT MEANSWHEREBY SAID TOBLOID IS EXPOSED TO GASES ON BOTH SIDES OF SAID SUPPORTMEANS.